I know how convenient is it to have an option to automatically add the fee, Scottt74480324. Although, the answer by DarellA is the only way to add this fee for now.

What I can do is take note of your concern and share it with our management team. This will be submitted to our product developers for assessment. This feature might be added in future updates.

I'll also add an article about how to enter late fees or finance and service charges on invoices as a future reference. 

You're always welcome to visit us if ever you need our help. We'd be happy to lend a hand.